User operated drug delivery devices are as such known in the art. They are typically applicable in circumstances, in which persons without formal medical training, i.e., patients, need to administer an accurate and predefined dose of a medicament, such as heparin or insulin. In particular, such devices have application, where a medicament is administered on a regular or irregular basis over a short-term or long-term period.
In order to accommodate with these demands, such devices have to fulfil a number of requirements. First of all, the device must be robust in construction, yet easy to use in terms of handling and in understanding by the user of its operation and the delivery of the required dose or medicament. The dose setting must be easy and unambiguous. Where the device is to be disposable rather than reusable, the device should be inexpensive to manufacture and easy to dispose.
Apart from manually or purely mechanically operated drug delivery devices there also exist electro-mechanical drug delivery devices wherein dose selection and administration of an appropriate dose of the medicament is controlled by way of electronic circuitry, for example a controller, a microprocessor, and/or the like. Such electronic or electro-mechanical devices provide a high dosing accuracy and may support long-term monitoring of doses dispensed by the device. Hence, a dosing and dispensing scheme can even be stored in the device allowing to recall the dose dispensing history.
However, with electronic or electro-mechanical devices, setting and dispending of a dose might be less intuitive compared to an all-mechanically implemented device. In particular, with a mechanically implemented device, the user has to apply a certain injection force, thereby obtaining a force feedback. By introducing an electro-mechanical device and replacing an all-mechanical device, the patient or user may be confronted with an unfamiliar or inconvenient operation scheme. Hence, there may emerge a certain danger of misuse and suboptimal medical treatment. Also, the acceptance of such an electro-mechanical device by the user may be rather low.
It is therefore an object of the present invention to provide an electro-mechanical drug delivery device providing a higher level of user acceptance, especially with users that are accustomed to mechanically implemented devices. Hence, the invention aims to enhance user compliance for electro-mechanically implemented devices. With the invention, users that are used to the functionality of a mechanical drug delivery device should become accustomed to an electrically driven device more easily.